Edging closer to streap+gunzip

requests.

This should make it possible to deliver arbitrarily sized objects
with pass mode.

when we need it.

front when unbusy'ing.  This should still keep the list roughly sorted in
Date: order, but keep the busy objects out of the way for lookups.

from storage.  Asking for more than 256M at a time will not
actually improve performance and is quite likely to hurt it.

the second of two headers in a row.

Fixes	#902

Fixes #825

NetBSD returns EINVAL when the other end unexpectedly shuts down the
connection, the same as Solaris, but on NetBSD it is documented.

If there was more than one of the User-Agent, Referer, Authorization,
X-Forwarded-For or Host header in a request, varnishncsa would leak
some memory.  We now just use the last value.

Fixes #898

Thanks to omes and vorpal for diagnosis and patch

Fixes	#891

Now for all the hard bits...

Start streaming response code

NB: no streaming happening yet.

Thanks to Magnus Hagander for spotting one of those.

Use an int rather than a char for counting.

Thanks to Thierry for the diagnosis.

Fixes #896

The syntax for enabling ESI has changed in trunk, update the
documentation to match.